Montpelier Re Holdings Ltd. Announces Common Stock Offering

Hamilton, Bermuda: 16 September 2005 - Montpelier Re Holdings Ltd. (NYSE: MRH - News) announced today that it has sold 25,850,926 shares of its common stock. The stock was reoffered at $24.00. Lehman Brothers Inc. acted as sole underwriter on the transaction. All shares were offered by the Company and were sold under the Company's Form S-3 shelf registration statement, which was declared effective on February 23rd, 2004.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of the common shares in any state in which such an offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such state.

A prospectus supplement relating to the offering will be filed with the Securities and Exchange Commission. When available, copies of the prospectus supplement and accompanying base prospectus relating to the offering may be obtained from Lehman Brothers by contacting Lehman Brothers, c/o ADP Financial Services, Prospectus Fulfillment, 1155 Long Island Avenue, Edgewood, NY 11717, email: monica_castillo@adp.com, fax: 631-254-7268.

Montpelier Re Holdings Ltd., through its operating subsidiary Montpelier Reinsurance Ltd., is a premier provider of global property and casualty reinsurance and insurance products. Additional information can be found in Montpelier's public filings with the Securities and Exchange Commission.

Application of the Safe Harbor of the Private Securities Litigation Reform Act of 1995:

This press release contains, and Montpelier may from time to time make, written or oral "forward-looking statements" within the meaning of the U.S. federal securities laws, which are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. All forward-looking statements rely on a number of assumptions concerning future events and are subject to a number of uncertainties and other factors, many of which are outside Montpelier's control that could cause actual results to differ materially from such statements. In particular, statements using words such as "may", "should", "estimate", "expect", "anticipate", "intend", "believe", "predict", "potential", or words of similar import generally involve forward-looking statements.

Important events and uncertainties that could cause the actual results, future dividends or future repurchases to differ include, but are not necessarily limited to: market conditions affecting Montpelier's common share price; our short operating and trading history; our dependence on principal employees; the cyclical nature of the reinsurance business; the levels of new and renewal business achieved; opportunities to increase writings in our core property and specialty reinsurance and insurance lines of business and in specific areas of

the casualty reinsurance market; the estimates reported by syndicates under existing QQS contracts; the inherent uncertainties of establishing reserves for loss and loss adjustment expenses, particularly on longer-tail classes of business such as casualty; unanticipated adjustments to premium estimates; the possibility of severe or unanticipated losses from natural or man-made catastrophes; the impact of terrorist activities on the economy; competition resulting from: growing capital levels in the reinsurance industry, in some cases, declining demand due to, among other things, increased retentions by cedants, and other factors; and rating agency policies and practices. Montpelier's forward-looking statements concerning market fundamentals could be affected by changes in demand, pricing and policy term trends and competition. These and other events that could cause actual results to differ are discussed in detail in "Risk Factors" contained in Item 1 of Montpelier's Annual Report on Form 10-K for the year ended December 31, 2004 filed with the Securities and Exchange Commission.

Montpelier undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date on which they are made.